would this work?

[JTStarlet92]

I was looking around the interwebs earlier and found this about a tercel > GT rear disc conversion, if it can be done on the tercel, can it not be done on UK spec cars? Looks easy enough

http://www.tercelreference.com/articles/rear_brake_conversion/rear_brake_conversion.html

[Rob H@RCH Engineering]

the GT axle bolts straight onto the starlet you just need the cables